support importdescriptors cmd of Core 0.21

doc-hex · doc-hex · commit 3151369e6795 · 2021-09-02T11:55:32.000-04:00
diff --git a/docs/bitcoin-core-usage.md b/docs/bitcoin-core-usage.md
@@ -5,8 +5,36 @@ needs a USB connection and additional software such as [HWI](https://github.com/
 
 ## Setup Steps
 
+### Bitcoin Core v0.21.0+
+
+As of Coldcard firmware v4.1.3, we recommend using the "importdescriptors"
+command with a native descriptor wallet in Core, so Core can generate
+and receive PSBT files natively from the GUI. The resulting wallet is
+no longer just a watch wallet, but can be used for spending by creating
+PSBT files for signing offline at the Coldcard.
+
+Step 1: Create a new descriptor-based wallet in Bitcoin Core
+
+- File -> Create Wallet ... 
+- give it a unique name
+- check "Descriptor Wallet"
+
+Step 2: Export descriptor from Coldcard to Core
+
+- on Coldcard, go to Advanced -> MicroSD card -> Export Wallet -> Bitcoin Core
+- on your computer, open `bitcoin-core-XX.txt`, copy the `importdescriptor` command line
+- in Bitcoin Core, go to Windows -> Console
+- select your newly created descriptor wallet in the wallet pulldown (top left)
+- paste the `importdescriptor` command. It should respond with a success message
+
+NOTE: If you are importing an existing wallet this way, with UTXO on the blockchain,
+you may need to rescan and/or delete "timestamp=now" from the command. If the
+balance is zero this is why.
+
 ### Bitcoin Core v0.19.0+
 
+(no longer recommended)
+
 For compatibility with other wallet software we use the BIP84 address derivation
 (m/84'/0'/{account}'/{change}/{index}) and native SegWit (bech32) addresses. It's
 recommended to set `addresstype=bech32` in [bitcoin.conf](https://github.com/bitcoin/bitcoin/blob/9546a785953b7f61a3a50e2175283cbf30bc2151/doc/bitcoin-conf.md).
@@ -19,8 +47,8 @@ The public keys can exported via an SD card, or via USB.
 
 To export via SD card:
 
-- go to Advanced -> MicroSD card -> Bitcoin Core
-- on your computer open public.txt, copy the `importmulti` command
+- go to Advanced -> MicroSD card -> Export Wallet -> Bitcoin Core
+- on your computer open `bitcoin-core-XX.txt`, copy the `importmulti` command line
 - in Bitcoin Core, go to Windows -> Console
 - select Coldcard in the wallet dropdown
 - paste the `importmulti` command. It should respond with a success message
@@ -46,6 +74,11 @@ createwallet Coldcard true
 
 ## Day-to-day Operation
 
+### Bitcoin Core v0.21.0+
+
+PSBT files can be directly created and loaded from the Bitcoin Core Qt GUI! HWI is not
+required, and air-gap via MicroSD is easy to use.
+
 ### Bitcoin Core v0.18.0+
 
 See HWI [instructions for usage](https://github.com/bitcoin-core/HWI/blob/master/docs/bitcoin-core-usage.md#usage).
diff --git a/releases/ChangeLog.md b/releases/ChangeLog.md
@@ -1,5 +1,9 @@
 ## 4.1.3 - Sep 2, 2021
 
+- Enhancement: support "importdescriptors" command in Bitcoin Core 0.21 so that
+  a descriptor-based wallet is created. PSBT files are then supported natively by
+  Core, and the resulting desktop wallet can be used for spending (ie. create PSBT
+  via GUI) and also watching. Translation: Easy air-gap PSBT operation with Bitcoin Core!
 - Enhancement: remove "m/0/0" derivations from public.txt and address explorer,
   since that path is obsolete and not used by any major wallets now. We can still
   sign PSBT files with that path, but it's an unnecessary risk to show derived
diff --git a/shared/export.py b/shared/export.py
@@ -162,7 +162,14 @@ async def make_bitcoin_core_wallet(account_num=0, fname_pattern='bitcoin-core.tx
 
     # make the data
     examples = []
-    payload = ujson.dumps(list(generate_bitcoin_core_wallet(examples, account_num)))
+    imp_multi = []
+    imp_desc = []
+    for a,b in generate_bitcoin_core_wallet(account_num, examples):
+        imp_multi.append(a)
+        imp_desc.append(b)
+
+    imp_multi = ujson.dumps(imp_multi)
+    imp_desc = ujson.dumps(imp_desc)
 
     body = '''\
 # Bitcoin Core Wallet Import File
@@ -178,19 +185,26 @@ async def make_bitcoin_core_wallet(account_num=0, fname_pattern='bitcoin-core.tx
 The following command can be entered after opening Window -> Console
 in Bitcoin Core, or using bitcoin-cli:
 
-importmulti '{payload}'
+importdescriptors '{imp_desc}'
+
+### Bitcoin Core before v0.21.0 
+
+This command can be used on older versions, but it is not as robust
+and "importdescriptors" should be prefered if possible:
+
+importmulti '{imp_multi}'
 
 ## Resulting Addresses (first 3)
 
-'''.format(payload=payload, xfp=xfp, nb=chains.current_chain().name)
+'''.format(imp_multi=imp_multi, imp_desc=imp_desc, xfp=xfp, nb=chains.current_chain().name)
 
     body += '\n'.join('%s => %s' % t for t in examples)
 
     body += '\n'
 
     await write_text_file(fname_pattern, body, 'Bitcoin Core')
 
-def generate_bitcoin_core_wallet(example_addrs, account_num):
+def generate_bitcoin_core_wallet(account_num, example_addrs):
     # Generate the data for an RPC command to import keys into Bitcoin Core
     # - yields dicts for json purposes
     from descriptor import append_checksum
@@ -226,17 +240,32 @@ def generate_bitcoin_core_wallet(example_addrs, account_num):
             coin_type=chain.b44_cointype,
             account=0,
             xpub=xpub,
-            change=(1 if internal else 0))
+            change=(1 if internal else 0) )
+
+        desc = append_checksum(desc)
 
-        yield {
-            'desc': append_checksum(desc),
+        # for importmulti
+        imm = {
+            'desc': desc,
             'range': [0, 1000],
             'timestamp': 'now',
             'internal': internal,
             'keypool': True,
             'watchonly': True
         }
 
+        # for importdescriptors
+        imd = {
+            'desc': desc,
+            'active': True,
+            'timestamp': 'now',
+            'internal': internal,
+        }
+        if not internal:
+            imd['label'] = "Coldcard " + txt_xfp
+
+        yield (imm, imd)
+
 def generate_wasabi_wallet():
     # Generate the data for a JSON file which Wasabi can open directly as a new wallet.
     import ustruct, version
diff --git a/testing/api.py b/testing/api.py
@@ -112,7 +112,7 @@ def doit(*parts):
 @pytest.fixture(scope='function')
 def bitcoind_wallet(bitcoind):
     # Use bitcoind to create a temporary wallet file, and then do cleanup after
-    # - wallet will not have any keys, and is watch only
+    # - wallet will not have any keys, and is watch-only
     import os, shutil
 
     fname = '/tmp/ckcc-test-wallet-%d' % os.getpid()
@@ -137,5 +137,38 @@ def bitcoind_wallet(bitcoind):
     assert fname.startswith('/tmp/ckcc-test-wallet')
     shutil.rmtree(fname)
 
+@pytest.fixture(scope='function')
+def bitcoind_d_wallet(bitcoind):
+    # Use bitcoind to create a temporary DESCRIPTOR-based wallet file, and then do cleanup after
+    # - wallet will not have any keys until a descriptor is added, and is not just watch-only
+    import os, shutil
+
+    fname = '/tmp/ckcc-test-desc-wallet-%d' % os.getpid()
+
+    disable_private_keys = True
+    blank = True
+    password = None
+    avoid_reuse = False
+    descriptors = True
+    w = bitcoind.createwallet(fname, disable_private_keys, blank,
+                                            password, avoid_reuse, descriptors)
+
+    assert w['name'] == fname
+
+    # give them an object they can do API calls w/ rpcwallet filled-in
+    cookie = get_cookie()
+    url = 'http://' + cookie + '@' + URL + '/wallet/' + fname.replace('/', '%2f')
+    #print(url)
+    conn = AuthServiceProxy(url)
+    assert conn.getblockchaininfo()['chain'] == 'test'
+
+    yield conn
+
+    # cleanup
+    bitcoind.unloadwallet(fname)
+    assert fname.startswith('/tmp/ckcc-test-desc-wallet')
+    shutil.rmtree(fname)
+
+
 
 # EOF
diff --git a/testing/conftest.py b/testing/conftest.py
@@ -5,7 +5,7 @@
 from ckcc.protocol import CCProtocolPacker, CCProtoError
 from helpers import B2A, U2SAT, prandom
 from api import bitcoind, match_key, bitcoind_finalizer, bitcoind_analyze, bitcoind_decode, explora
-from api import bitcoind_wallet
+from api import bitcoind_wallet, bitcoind_d_wallet
 from binascii import b2a_hex, a2b_hex
 from constants import *
 
diff --git a/testing/test_export.py b/testing/test_export.py
@@ -12,9 +12,10 @@
 import json
 from conftest import simulator_fixed_xfp, simulator_fixed_xprv
 from ckcc_protocol.constants import AF_CLASSIC, AF_P2WPKH, AF_P2WSH_P2SH
+from pprint import pprint
 
 @pytest.mark.parametrize('acct_num', [ None, '0', '99', '123'])
-def test_export_core(dev, acct_num, cap_menu, pick_menu_item, goto_home, cap_story, need_keypress, microsd_path, bitcoind_wallet):
+def test_export_core(dev, acct_num, cap_menu, pick_menu_item, goto_home, cap_story, need_keypress, microsd_path, bitcoind_wallet, bitcoind_d_wallet):
     # test UX and operation of the 'bitcoin core' wallet export
     from pycoin.contrib.segwit_addr import encode as sw_encode
 
@@ -51,14 +52,21 @@ def test_export_core(dev, acct_num, cap_menu, pick_menu_item, goto_home, cap_sto
 
     path = microsd_path(fname)
     addrs = []
-    js = None
+    imm_js = None
+    imd_js = None
     with open(path, 'rt') as fp:
         for ln in fp:
             if 'importmulti' in ln:
+                # PLAN: this will become obsolete
                 assert ln.startswith("importmulti '")
                 assert ln.endswith("'\n")
-                assert not js, "dup importmulti lines"
-                js = ln[13:-2]
+                assert not imm_js, "dup importmulti lines"
+                imm_js = ln[13:-2]
+            elif "importdescriptors '" in ln:
+                assert ln.startswith("importdescriptors '")
+                assert ln.endswith("'\n")
+                assert not imd_js, "dup importdesc lines"
+                imd_js = ln[19:-2]
             elif '=>' in ln:
                 path, addr = ln.strip().split(' => ', 1)
                 assert path.startswith(f"m/84'/1'/{acct_num}'/0")
@@ -70,15 +78,51 @@ def test_export_core(dev, acct_num, cap_menu, pick_menu_item, goto_home, cap_sto
 
     assert len(addrs) == 3
 
-    obj = json.loads(js)
     xfp = xfp2str(simulator_fixed_xfp).lower()
 
+    if imm_js:
+        obj = json.loads(imm_js)
+        for n, here in enumerate(obj):
+            assert here['range'] == [0, 1000]
+            assert here['timestamp'] == 'now'
+            assert here['internal'] == bool(n)
+            assert here['keypool'] == True
+            assert here['watchonly'] == True
+
+            d = here['desc']
+            desc, chk = d.split('#', 1)
+            assert len(chk) == 8
+            assert desc.startswith(f'wpkh([{xfp}/84h/1h/{acct_num}h]')
+
+            expect = BIP32Node.from_wallet_key(simulator_fixed_xprv)\
+                        .subkey_for_path(f"84'/1'/{acct_num}'.pub").hwif()
+
+            assert expect in desc
+            assert expect+f'/{n}/*' in desc
+
+        # test against bitcoind
+        for x in obj:
+            x['label'] = 'testcase'
+        bitcoind_wallet.importmulti(obj)
+        x = bitcoind_wallet.getaddressinfo(addrs[-1])
+        pprint(x)
+        assert x['address'] == addrs[-1]
+        if 'label' in x:
+            # pre 0.21.?
+            assert x['label'] == 'testcase'
+        else:
+            assert x['labels'] == ['testcase']
+        assert x['iswatchonly'] == True
+        assert x['iswitness'] == True
+        assert x['hdkeypath'] == f"m/84'/1'/{acct_num}'/0/%d" % (len(addrs)-1)
+
+    # importdescriptors -- its better
+    assert imd_js
+    obj = json.loads(imd_js)
     for n, here in enumerate(obj):
-        assert here['range'] == [0, 1000]
+        assert range not in here
         assert here['timestamp'] == 'now'
         assert here['internal'] == bool(n)
-        assert here['keypool'] == True
-        assert here['watchonly'] == True
 
         d = here['desc']
         desc, chk = d.split('#', 1)
@@ -91,18 +135,21 @@ def test_export_core(dev, acct_num, cap_menu, pick_menu_item, goto_home, cap_sto
         assert expect in desc
         assert expect+f'/{n}/*' in desc
 
-    # test against bitcoind
-    for x in obj:
-        x['label'] = 'testcase'
-    bitcoind_wallet.importmulti(obj)
-    x = bitcoind_wallet.getaddressinfo(addrs[-1])
-    from pprint import pprint
-    pprint(x)
-    assert x['address'] == addrs[-1]
-    assert x['label'] == 'testcase'
-    assert x['iswatchonly'] == True
-    assert x['iswitness'] == True
-    assert x['hdkeypath'] == f"m/84'/1'/{acct_num}'/0/%d" % (len(addrs)-1)
+        if n == 0:
+            assert here['label'] == 'Coldcard ' + xfp
+
+        # test against bitcoind -- needs a "descriptor native" wallet
+        bitcoind_d_wallet.importdescriptors(obj)
+
+        x = bitcoind_d_wallet.getaddressinfo(addrs[-1])
+        pprint(x)
+        assert x['address'] == addrs[-1]
+        assert x['iswatchonly'] == False
+        assert x['iswitness'] == True
+        assert x['ismine'] == True
+        assert x['solvable'] == True
+        assert x['hdmasterfingerprint'] == xfp2str(dev.master_fingerprint).lower()
+        #assert x['hdkeypath'] == f"m/84'/1'/{acct_num}'/0/%d" % (len(addrs)-1)
 
 def test_export_wasabi(dev, cap_menu, pick_menu_item, goto_home, cap_story, need_keypress, microsd_path):
     # test UX and operation of the 'wasabi wallet export'
